Details of reduced government spending in the future began to take shape today as, one by one, Whitehall departments issued figures for efficiency savings.

In an embellishment to the usual hour-long lunchtime budget delivered by the chancellor, the afternoon was filled by the drip-drip publication of efficiency savings found by the 16 individual Whitehall departments as the Treasury sought to underscore that every area of government had been made to carry out an audit.

The government announced in its November pre-budget report that it would be finding annual £11bn savings in spending across Whitehall but, until today, had not revealed precise plans.

The cabinet minister making the largest trim to his budget was the health secretary, Andy Burnham, who offered up more than a third of the total savings, cutting £4.35bn. He said his department could save £1.5bn by driving down the cost of procurement, £100m from IT programmes, £60m from reducing energy consumption and £555m by reducing staff sickness and absence.

Other notable cuts include £1.1bn from Ed Balls's Department for Children, Schools and Families, £431m from the Ministry of Justice, which will include the closure of 20 magistrates courts, and £700m from the politically sensitive Ministry of Defence budget, although Alistair Darling pointedly pledged to maintain the £4bn spend on the Afghan war.

All ministers emphasised that the total cuts would all come from "back-office savings" – improvements in how they buy equipment, IT and their estates – while protecting frontline services.

Within the £11bn total, £8bn would come from even more specific operational efficiencies such as cleaning contracts, management of payrolls and technical support. In addition, there will be a 50% reduction in spending on consultants by Whitehall departments, alongside a 25% cut in marketing and communications budgets which together save £650m by April 2013.

The government will save £500m from reduced spending on IT programmes and £1.4bn from reducing civil service pay and days lost to sickness, £300m from reducing spending on energy and £500m from reforms to subsidiary bodies.

However, there was irritation at the manner of the staggered announcements throughout the afternoon and questions about why the chancellor had not detailed the individual department cuts in his statement, enabling it to be debated in the house. The opposition charged it was an attempt to distract attention from the budget itself.

There was incredulity from the opposition over some specific pledges – most notably that made by the Department of Health to make such large savings on staff sickness – but also over the wisdom of the entire exercise.

The Tories added that without a comprehensive spending review for the years over which these savings would be made, there is no baseline against which to measure possible savings after 2011. They also said that even factoring in the £11bn of cuts, there was still some £20bn to £25bn in a shortfall.

Vince Cable, the Liberal Democrat Treasury spokesman, said the programme was "totally vacuous". He said: "If it's inefficiency, why has it been tolerated all these years?"

The newly detailed cuts will also be poorly received by many public sector workers already striking over changes to their pay and conditions.

Alongside the £8bn of so-called operational efficiencies, the government also gave details of how it would find efficiencies from elsewhere in government, going further on how it planned to relocate public servants out of Whitehall.

The chief secretary to the Treasury, Liam Byrne, has already announced in his Smarter Government document the intention to consult on relocating civil servants out of London.

Darling said the number of civil servants in London will be reduced by a third over the long term, with 15,000 posts relocated within the next five years. The Ministry of Justice announced that it would be relocating 1,000 civil servants out of London by 2015 and will rationalise its estate from 18 sites to four, saving £41m a year by 2015.

While the chancellor delivered his budget, civil servants mounted picket lines outside parliament as part of a national strike over redundancy pay. Trade union leaders have complained that the relocation has cost jobs and forced some staff to seek alternative work because their families were unwilling or unable to move.

Departments which have switched work from the capital in recent years include the Health and Safety Executive (to Bootle on Merseyside) and the Office for National Statistics (to Newport in South Wales).

"Relocation should be done with the consent of the workforce," said a spokesman for the Public and Commercial Services union. "The government also needs to recognise that people have family ties and many are dual earners, with the partners of civil servants having a job in London. Civil servants should not be forced out of a job at the whim of politicians. There needs to be a sound business case."

The budget book shows progress made on asset sales and reveals that British Waterways, which looks after the country's 2,200 miles of canals and rivers – has been saved from a sell-off and instead will be turned into a mutualised public service.

This will keep the waterways in the public sector, as they have been since 1947, and British Waterways may now to resemble a "national trust". There were plans to sell off attractive British Waterways properties, a process from which it has raised £45m a year.